The present invention generally relates to percutaneous leads for medical or surgical uses, such leads being capable of performing multiple functions, such as mapping or pacing, in connection with the diagnosing or treatment of cardiac conditions, the leads being particularly well suited for use as disposable, temporary treatment devices.
Electrophysiological studies and treatments of patients have in the past utilized many different devices and systems including those that incorporated an elongated percutaneous lead that provides an electrically conductive elongated pathway between a location that is external of the patient and a location within the patient at which sensing, stimulation or treatment is to take place. When this percutaneous route is taken in conjunction with studies or treatment of the heart, this is known as an endocardial approach. While an epicardial approach is possible, this is not always the most suitable procedure since it requires thoractomy and the exposure of the heart. Endocardial approaches are typically preferred because they are substantially less intrusive. Such procedures typically require accurate location of each electrode at specific locations on cardiac tissue.
The pacing function is well known in the art, whereby an electrical impulse is imparted to a particular location of the body in order to either assist proper functioning of a body organ or in order to control or bring under control an iatrogenic or spontaneous dysrhythmia by pacing a ventricle, or in order to stimulate or pace the heart so as to assist in mapping its electrical pathways. Regarding the mapping function, such is undertaken to identify specific foci or anatomical locations which, for example, are a source of abnormal cardiac rhythm in patients with dysrhythmias.
While the foregoing functions may be readily performed while following the epicardial approach involving the exposure of the heart, there is a need for a more sophisticated and thorough utilization of these functions in connection with the substantially less intrusive endocardial approach. Accordingly, there is a need for a device that has the attributes of the less intrusive endocardial approach while still providing substantial control, adjustability and feasibility for studies and treatments including those involving any or all of pacing or mapping leads.
In addition to the foregoing, when an attempt is made to carry out multiple testing and/or treating functions of the type described using the endocardial approach, the use of two temporary pervenous leads is often required. One lead is needed for the ventricle and the other is needed for the atrium, and the introduction of the second lead in the same vein or in a second access site can dislodge the first lead from its position in the chamber of choice. In certain patients, veins of adequate diameter to accept two leads may be a limiting factor. Generally, insertion of a pervenous lead for short-term use is accomplished under conditions where time is an important factor. Endocardial pacing or mapping accuracy, speed and efficiency are typically quite difficult to achieve when utilizing two separate leads for multiple functioning or when even using a single lead provided with multiple functioning stations which are generally stationarily fixed relative to one another thereby making it difficult to modify the mapping surface or pacing electrode locations.
The size and configuration of hearts may vary somewhat substantially, and difficulty has been encountered in achieving and maintaining reliable contact with the atrial muscle during endocardial procedures. The surfaces being paced or mapped usually will be concave or generally flat, but unless the electrodes of the pacing or mapping assemblies exhibit some degree of adjustability, it is not possible to have the same device pace or map such a variety of surface configurations. This type of adjustability is rendered more difficult when such must be provided for in an endocardial device which, ideally, should be isodiametric throughout the length of the device. Various curves along the length of the lead or the addition of various appendages to the lead may cause difficulties not only during endocardial insertion but also during removal attempts.
Accordingly, there is a need for a multiple functioning percutaneous lead to achieve endocardial pacing, mapping and other procedures which may be readily inserted and removed under conditions where time is an important factor, and which is capable of establishing and maintaining reliable contact with the portions of the heart undergoing testing and/or treatment. A general object of the present invention is to provide such a lead which exhibits adjustability between isodiametric and outwardly extending electrode configurations.
Another object of this invention is to provide an improved percutaneous lead that functions in the manner of an endocardial catheter that can be guided through a narrow body passageway such as a vein or an artery when it has a substantially isodiametric configuration, but which can, after it has been properly positioned within the body, be manipulated such that distal electrodes are movable outwardly therefrom to establish effective ventricular and atrial surface contact in hearts of variable size and configuration, thus providing effective mapping and/or pacing functions.
Still another object of the present invention is to provide a readily insertable and removable ventricular/atrial pervenous lead for cardiac pacing or diagnosis which is relatively inexpensive and disposable and which, in its pervenous advanceable and retractable condition, is isodiametric.
An additional object of the present invention is to provide an adjustable isodiametric atrial-ventricular pervenous lead of the type described which is readily manipulated externally of the body to independently adjustably place multiple electrode assemblies in effective contact with surfaces of the heart undergoing diagnosis and/or treatment.